new gears without chip?

[SouLRioT]

Hey I found this at fordracing:

Q.: I have changed the gears in my Mustang; how do I correct the speedometer?

A.: Changing your axle gear ratio can throw off the calibration of your speedometer, so purchasing a different speedometer drive gear from your local Ford or Lincoln/Mercury dealer will be necessary for your speedometer to more accurately reflect actual readings. A speedometer gear usage chart is printed on Page 129 in the 2004 FRPP catalog that can guide you to the proper speedometer gear needed to correct your speedometer. For applications not listed there, or if you have a 1999 and newer Mustang, call the FRPP Tech "Hot Line" (586-468-1356) to get specific speedometer correction advice


Anyone done this, or even thought about doing it without buying a chip?

[BillyGman]

We cannot do that w/our Marauders since new cars no longer run off a speedometer gear. They no longer have a speedometer cable anymore that goes to the Transmission, because the speedometer is controlled by the computer. So that's why you have to get a chip to correct the speedo error that the gear ratio change causes.

[Fourth Horseman]

If you don't want a chip, or if you're going to wait a bit on a chip, your Ford/Mercury dealer should be able to re-flash your computer to calibrate the speedometer correctly for the new gears. At least, that's what my local service manager told me.

[FordNut]

If you don't want a chip, or if you're going to wait a bit on a chip, your Ford/Mercury dealer should be able to re-flash your computer to calibrate the speedometer correctly for the new gears. At least, that's what my local service manager told me.

That's news to me. They claimed they couldn't do it when I first changed mine, but that was over a year ago. But I saw in an old, old post that claimed the system could automatically sense gear ratio changes up to 3.73 I haven't verified that statement for accuracy. Not much help anyway since most changes are for 4.10s.

[CRUZTAKER]

It has always been my understanding that the dealer DOES NOT have this type of software available to them. They only have what there is a part number for, ie. updates etc, not speedo calibration.

Get a chip or a tuner, cause that's the onlty way you're gonna fix it.

[TripleTransAm]

I was also told the same... dealer didn't have the s/w to change the gear ratio.

[Fourth Horseman]

Very well could be that the dealer I talked to is wrong. But I did hear this from both one of their service writers and the service manager, for whatever that's worth.